1. Field of the Invention
The present invention relates to a portable telephone apparatus. More particularly, the present invention relates to a portable telephone apparatus having an antenna diversity effect.
2. Description of the Related Art
Conventionally, an antenna of a portable telephone apparatus is disposed on an upper side of the portable telephone apparatus located on a side on which a receiver is disposed.
FIG. 1 is a view showing an arrangement configuration of an antenna of a conventional foldable portable telephone apparatus. This employs the configuration having: a lower body 81 with a microphone and a keyboard; an upper body 82 with a display and a receiver, which is coupled through a hinge to the body 81 in a foldable manner; and an antenna 83 disposed on an upper side of the upper body.
W-CDMA (wideband CDMA) that is the as a next generation of a portable telephone system employs a receiving system different from a current system of a PDC system, in which a continuous reception and a continuous transmission are carried out together with a transmission operation and a reception operation.
The conventional portable telephone apparatus employs an upper antenna arrangement in which an antenna is disposed on a receiver side. So, in a call condition that the portable telephone apparatus is used in contact with an ear, the upper antenna approaches a head of a human body. Thus, this results in a problem of a deterioration in a property of the antenna.
When the W-CDMA portable telephone system uses the antenna diversity method, a base station can employ a RAKE reception manner of synthesizing the arriving arrival waves with temporal differences from each other, increasing a reception power and improving a sensibility. At this time, it is possible to take a measure, such as a measure that when one reception state is poor, the other antenna is used to receive.
However, the transmission operation and the reception operation as well as the continuous reception and the continuous transmission are carried out. So, the employment of the antenna diversity method for switching between the two antennas results in the problem that a reception data becomes erroneous the moment of the switching between the antennas, and a normal reception and a normal transmission can not be done.
As the measure against such problems, a method may be considered for employing a manner in which an antenna is disposed on a lower portion implying a mount side of a transmitter in the portable telephone apparatus. Also in this case, the W-CDMA communication system can not carry out the antenna diversity.
Japanese Laid Open Patent Application (JP-A-Heisei, 9-93322) discloses the following portable telephone apparatus. This portable telephone apparatus is characterized in that respective micro strip antennas for reception and transmission are disposed on the substantially same planes in a predetermined interval and have resonance frequencies different from each other although they are positioned close to each other.
Japanese Laid Open Patent Application (JP-A-Heisei, 10-154955) discloses the following portable telephone apparatus. This portable telephone apparatus has a plurality of antennas, switches and selects an antenna having an allowable reception level, and carries out a reception. This portable telephone apparatus is provided with: a switching operation detector for detecting the switching operation of the antenna; and a high speed shift state judge device for judging that the portable telephone apparatus is at a high speed shift state if a frequency of the switching operations detected by the switching operation detector exceeds a predetermined value.
Japanese Laid Open Patent Application (JP-A, 2000-13276) discloses the following radio communication device. This radio communication device is provided with a transmission/reception whip antenna, a reception diversity antenna, a transmission circuit, a reception circuit, and an antenna switch disposed between the transmission/reception whip antenna, the reception diversity antenna, the transmission circuit and the reception circuit. This radio communication device is characterized in that a load matching circuit is mounted between a final stage power amplifier of the transmission circuit and the antenna switch.
Japanese Laid Open Patent Application (JP-A, 2000-22609) discloses the following portable radio communication device. In this portable radio communication device, a transmission/reception circuit having a transmission circuit and a reception circuit, a plurality of flat antennas having a substantially single directivity, a power synthesizer and a power distributor are accommodated within a body in a form of substantially rectangular parallelepiped. Each of the plurality of flat antennas is disposed on a different surface within the body. A transmission signal outputted by the transmission circuit is sent through the power distributor to each of the plurality of flat antennas. A reception signal received by the plurality of flat antennas is sent through the power synthesizer to the reception circuit.
Japanese Laid Open Patent Application (JP-A, 2000-59256) discloses the following fixed antenna device. This fixed antenna device has the following feature. That is, in an antenna used in a portable telephone apparatus, a movable electromagnetic shield plate opposite to a tapered antenna element is disposed at a position of a front direction of a body, parallel to the tapered antenna element fixed on an upper portion of the body. Then, the shield state of an electromagnetic wave to the front direction of the body from the tapered antenna element is varied by moving the movable electromagnetic shield plate upward and downward.